CN106662439A - Distortion prediction and minimisation in additive manufacturing - Google Patents

Abstract

A method of minimising distortion in a workpiece is described that includes utilizing a computer system to carry out finite element analysis on a finite element thermo- mechanical model of the workpiece during and after fabrication by additive manufacturing to predict shape distortion and residual stress development in the workpiece, wherein the fabrication includes the fabrication step of depositing multiple layers of a material melted by a heat source along a deposit path on a substrate, and introducing alterations to the workpiece prior to or during fabrication to compensate for the predicted distortion.

Description

The prediction deformed in increasing material manufacturing and minimum

Technical field

The disclosure is usually directed to increasing material manufacturing, puts continuous metal material layer in increasing material manufacturing and is laid on substrate, especially It is related to predict and minimize the deformation during increasing material manufacturing is processed.It is convenient to describe and manufactured with electron beam free forming (EBFFF) prediction of the deformation of the Demonstration Application correlation of the customization metal parts prepared by and minimum, it should be appreciated that , specification is not limited only to the Demonstration Application, but with the general applicability of the increasing material manufacturing to other forms.

Background technology

Increasing material manufacturing is had become for the essential industry process of manufacture customization metal parts.EBFFF is also known as electricity Beamlet increasing material manufacturing (EBAM), is quick metal deposition process that a kind of various solderable alloys of effectively utilizes carry out operation.Open The 3D models of the CAD program of the part for wanting construction are started from, EBFFF process is by the way that metal wire feedstock is introduced in vacuum environment The part is successively built on the substrate of metal using the molten bath that electron beam created and maintained for focusing on.Operation in vacuum Guarantee clean processing environment and need not can consume protective gas.

Already shown EBFFF process is a leading selection, for generating the prefabricated component of a large amount of nearly end forms.Channel syndrome It is bright, when compared to conventional treatment, notable cost savings can be realized using the process, this is the reduction used due to raw material And minimize the lead time.

Residual stress and shape distortion are the inherent features of increasing material manufacturing, especially need high heat to be input under high deposition rate To substrate and previous sedimentary, this causes larger thermal gradient.In most circumstances, after deposition to manufactured part It is heat-treated to contribute to mitigating stress.As a result, to cause viability premature failure heavily stressed presence worry unlike The worry of the deformation that the stress and stress during to deposition and after deposition causes is more.At present by frequently should during construction Power mitigation step is solving the residual stress related to EBFFF process and deformation.But, these steps are troubles, time-consuming, and And increased production cost using the prepared object of EBFFF process.

Expect stress mitigation step required during minimizing increasing material manufacturing.It is also expected to providing a kind of raising at increasing material manufacturing The mode of the efficiency of reason, especially preferably manages the deformation related to increasing material manufacturing and residual stress.It is also expected to providing a kind of The instrument of the deformation in for predicting increasing material manufacturing process, enabling take steps to compensate the deformation.

The content of the invention

In an arrangement, there is provided a kind of method of the minimizing deformation for making workpiece, comprise the steps：

In computer systems, to the limited during being manufactured by increasing material manufacturing and after manufacture of the workpiece First thermomechanical model carries out finite element analysis (FEA), to predict the shape distortion and residual stress development of workpiece, wherein, institute State the manufacturing step that manufacture includes the multilayer material melted by thermal source being deposited on along deposition path on substrate；And

Before manufacture or during manufacture the change to the workpiece is introduced into the deformation of compensation prediction.

In one or more embodiments, the manufacture further includes in following multiple manufacturing steps：Preheating The substrate, cools down the workpiece, and subsequently releases the mechanical constraint on the workpiece.

The thermal source can include it is following in one or more：Electron beam, welding arc, plasma arc and laser beam.

In one or more embodiments, to the substrate one in geometry and the deposition path or It is multiple to be modified.

In one or more embodiments, the model include heat transmission unit, for by substrate, deposition materials and Heat conduction model in one or more in the workbench of support group plate.

In one or more embodiments, the model is included for by from the workpiece to outside heat transfer model Heat transfer unit.

The heat transfer unit can be according to the heat radiation of workpiece by heat transfer model.

For example, above-mentioned heat transfer unit can be according to below equation by heat transfer model：

Wherein, q is heat flux, and T is temperature, T_ambIt is environment temperature, ε is surface emissivity, and σ is that Stefan-Boltzmann is normal Number.

The heat transfer unit can be according to the heat transfer of workpiece extraly by heat transfer model.

For example, the heat transfer unit can be according to below equation by heat transfer model：

Q=h (T-T_amb)

Wherein, q is heat flux, and T is temperature, T_ambIt is environment temperature.

In one or more embodiments, above-mentioned model can include using Hooke's law, the Young's modulus of material, Poisson Than the elastic deformation unit with thermal coefficient of expansion.

In one or more embodiments, the model includes following von mises (von Mises) yield criterion Yield behavior unit.

In one or more embodiments, the model includes yield behavior unit, and it follows the dependence for deriving by rule of thumb The flow stress data of temperature.

In one or more embodiments, the model includes material sedimentation unit, wherein, in liquidus temperature or slightly It is micro- a small amount of overheated by the deposition modeling of the material higher than utilizing under the liquidus temperature.

In one or more embodiments, the model includes solidification unit.

In one or more embodiments, the model includes material sedimentation unit, wherein, will be by applying energy/heat Source is deposition modeling to melt the material that the material is carried out.

In one or more embodiments, methods described further includes step：

Using from the stress analysis information of the finite element analysis come recognize local stress increase, using the thermal source One or more fabrication stages during need to mitigate the local stress and increase.

In one or more embodiments, methods described further includes step：

By not cooling down the workpiece between the deposition of the pantostrat of material, minimize in one or more manufactures From the substrate and the heat loss of the deposition materials during stage.

For example, the mean temperature that the workpiece can be prevented between the deposition of the pantostrat of material declines 10%.

In one or more embodiments, methods described further includes step：

By making workpiece adiabatic during manufacture, make during one or more fabrication stages from substrate and deposition materials Further minimum heat losses.

In one or more embodiments, methods described further includes step：

By applying radiation reflective to the workpiece, make during one or more fabrication stages from the substrate With the further minimum heat losses of the deposition materials.

In one or more embodiments, methods described further includes step：

By preheating the substrate before the material is deposited, thermal gradient between the workpiece and the substrate is made most Littleization.

In one or more embodiments, methods described further includes step：

Controlled at one or many by the reduction of the limit stress control clamping force changed according to cooling down with part Mechanical boundary conditions during the individual fabrication stage, form or other manufacturing defect to minimize either Crack prevention.

In one or more embodiments, the material is metal or metal alloy.

In one or more embodiments, the metal alloy is included in titanium, aluminium, nickel, vanadium, tantalum, copper, scandium, boron or magnesium It is any one or more of.

For example, metal alloy can be Titanium alloy Ti-6Al-4V.

A kind of computer implemented method of the deformation of prediction workpiece is provided in another arrangement, and the method includes following step Suddenly：

In computer systems, to the limited during being manufactured by increasing material manufacturing and after manufacture of the workpiece First thermomechanical model carries out finite element analysis to predict the shape distortion and residual stress development of workpiece, wherein, the manufacture Including the manufacturing step being deposited on multiple layers of the material melted by thermal source along deposition path on substrate.

In yet another aspect provide a kind of non-transient computer-readable medium, its series of instructions is encoded with Make computing device above computer implementation.

A kind of increasing material manufacturing device is provided in yet another aspect, it includes：

Thermal source；Wire feeder；Workbench, it is used for supporting substrate, and material deposition is carried out on the substrate；Travel mechanism, It is used to provide the relative movement of the thermal source, wire feeder and workbench；And vacuum chamber, its closing thermal source, wire feed Device, workbench and travel mechanism；And

Control device, it is used to control the operation of the thermal source, wire feeder, workbench and travel mechanism, and is used for Perform said method.

A kind of system for passing through the deformation in the workpiece manufactured by increasing material manufacturing for prediction is provided in another arrangement, Wherein, the manufacture includes the material melted by thermal source being deposited on substrate along deposition path, and the system includes：

Main storage, it is used to store the computer-readable code for Finite Element Method ＆ Its Application module；

At least one processor, it is attached to the main storage, primary storage described at least one computing device The computer-readable code in device, so that the application module is limited before manufacture and during manufacture to the workpiece First thermomechanical model carries out finite element analysis, to predict workpiece in shape distortion and/or residual stress development.

Description of the drawings

Hereinafter illustrate to be related to various embodiments in more detail.In order to be beneficial to understand, the refer to the attached drawing in explanation is schemed in accompanying drawing Specific embodiment is shown.It should be understood that in accompanying drawing embodiment illustrated be not construed as it is restricted.

In the accompanying drawings：

Fig. 1 shows the isometric view of multiple units of the direct manufacture device of electron beam；

Fig. 2 is for driving and controlling the servo control mechanism of the direct manufacture device of electron beam for being illustrated in Fig. 1 and control system The schematic diagram of system；

Fig. 3 is functional diagram, illustrates the selected part of example computer system, to predict in the device institute shown in Fig. 1 Deformation in the workpiece of manufacture, and alternatively to the control system offer data for being illustrated in Fig. 2, so that the dress shown in Fig. 1 Put the minimizing deformation of manufactured workpiece；

Fig. 4 is schematic diagram, shows the data of the software module of the computer system for being input to Fig. 3, should by software module With finite element analysis (FEA) model to the data, and the predicted stresses that generated by software module and deformation data and work Part changes data；

Fig. 5 and Fig. 6 show two examples of the workpiece geometries that stress and strain model is carried out using solid element, entity list Unit forms a part for the data being input in the software module of the computer system of Fig. 3；

Fig. 7 and Fig. 8 be the substrate of the workpiece shown in Fig. 5 and Fig. 6 and the thermal conductivity of deposition materials and specific heat temperature according to Curve map is deposited, curve map is included in finite element analysis (FEA) model of the part of the software module of the computer system to form Fig. 3 Heat transmission unit in；

Fig. 9 and Figure 10 are the substrate of the workpiece shown in Fig. 5 and Fig. 6 and the Young's modulus of deposition materials and thermal coefficient of expansion The interdependent curve map of temperature, curve map is included in the finite element analysis of the part of the software module of the computer system to form Fig. 3 (FEA) in the elastic deformation unit of model；

Figure 11 is the flowing of the temperature dependent for deriving by rule of thumb of the substrate of the workpiece shown in Fig. 5 and Fig. 6 and deposition materials The curve map of stress data, the curve figure is included in the finite element fraction of the part of the software module of the computer system to form Fig. 3 In the yield behavior unit of analysis (FEA) model；

(a) and (b) of Figure 12 respectively illustrates the schematic diagram of the T-shaped by manufactured by the device of Fig. 1 and cross-shaped part；

Figure 13 (a) illustrate for measuring the workpiece shown in Figure 12 in normal direction residual stress layout；

(b) and (c) of Figure 13 shows many of the residual stress measurement that the layout for being illustrated using Figure 13 (a) is performed The position of individual point；

(a) of Figure 14 to (c) shows three " thermal maps ", and they are illustrated when moulding deposition is completed, after cooling And in the demonstration T-shaped workpiece manufactured by the device by Fig. 1 from after fixture release, the predicted evolution of von mises stress；

Figure 15 shows that the modelling performed by the computer system by Fig. 3 is predicted and by " thermal map " expression The ratio deformed after figured moulding of the deformation with the measurement in the experiment moulding and by moulding after (and Figure 14 diagram) moulding Compared with；

Figure 16 (a) to (c) shows three " thermal maps ", they illustrate complete moulding deposit when, after cooling with And in demonstration X-shape workpiece from after fixture release, the predicted evolution of von mises stress；

(and Figure 116 figures that Figure 17 shows the model prediction performed by the computer system of Fig. 3 and represented by " thermal map " Show) after moulding deformation with measure in corresponding experiment moulding and after moulding by the graphical representation of moulding deformation comparison；

Figure 18 show based on Johnson-Cook models with collect experimental data, flow stress with temperature curve Figure；

Figure 19 is shown using " thermal map " of the longitudinal residual stress measured by neutron diffraction, and based on Johnson- " thermal map " of the residual stress that Cook models and the material model of renewal are predicted；

Figure 20 shows the image deformed from after the moulding measured by experiment moulding, and " thermal map " is shown by the calculating of Fig. 3 The figure that the modelling that machine system is carried out is predicted；

Figure 21 is that the figure of the change of the deformation that applicant considers selected experimental design result for experimental verification is illustrated；

Figure 22 shows temperature and Feng's rice predicted at the end of the moulding for the T-shaped part on pre-bend substrate Fill in " thermal map " of this stress distribution；

Figure 23 shown in the moulding using pre-bend substrate, Feng's rice after cooling and after fixture release Fill in " thermal map " of the predicted evolution of this stress；

Figure 24 shows that deformation is corresponding with what is described in image after the moulding predicted by the modelling illustrated in " thermal map " Comparison between the measurement deformation of experiment moulding；

Figure 25 illustrates the third example of the workpiece geometries that stress and strain model is carried out using solid element, solid element shape Into a part for the data being input in the software module of the computer system of Fig. 3；

Figure 26 to Figure 28 shows " thermal map ", and they illustrate the prediction workpiece geometry of Figure 25 during the various stages of manufacture Shape, wherein, prediction of distortion is not compensated；

Figure 29 to Figure 31 shows " thermal map ", and the prediction workpiece that they illustrate Figure 25 during the various stages of manufacture is several What shape, wherein, prediction of distortion is compensated；And

Figure 32 shows " thermal map " 474 of the prediction of distortion of the workpiece geometries of Figure 25, does not introduce deformation-compensated change, The image of manufactured workpiece, and illustrate " thermal map " of the prediction of distortion of model when deformation-compensated change is introduced into model.

Specific embodiment

With reference now to Fig. 1, show electron beam free forming manufacture (EBFFF) for manufacturing workpiece by increasing material manufacturing The unit for generally selecting of device 10.Device 10 obviously includes：Electron beam gun 12, it is used to generate electron beam 14, electron beam 14 For melting from wire feeder 18 metal wire feedstock 16 being supplied in the molten bath for being created by electron beam and being maintained.The He of electron beam gun 12 Wire feeder 18 relative to each other maintains fixed position, but can move along Y-axis line and z axis.Device 10 is further wrapped The workbench 20 for being suitable to support metal substrate 22 is included, by the operation of electron beam gun 12 and wire feeder 18 by the company of metal alloy 24 Subsequent layers are deposited on metal substrate 22.Workbench 20 can be shifted along X-axis line.In use, the phase of 12/ wire feeder of electron beam gun 18 For workbench 20 is shifted, to lay the continuous orbit of molten alloy, after deposition molten alloy solidifies again, to form the phase The material layer of prestige.

Fig. 2 shows electron beam gun 12, and it is included in sealing container or is able to maintain that the vacuum chamber 50 of vacuum environment In.Electron beam gun 12 is suitable to be generated and launching electronics beam 14 in vacuum environment, and is suitable to guide electronics towards substrate 22 Beam 14.In the arrangement that Fig. 1 describes, substrate 22 is positioned in workbench or movable platform 20.The part of rifle 12 can position In the outside of chamber 50, for being close to and being electrically connected.Alternatively, electron beam gun 12 can be fully enclosed in chamber 50 It is interior so that electron beam gun also can be moved, rather than only substrate 22 is moved.In either case, electron beam gun 12 Move relative to substrate 22.

Platform 20 and/or electron beam gun 12 can be moved via multi-axial cord Locating driver system 25, to put it more simply, in Fig. 1 Multi-axial cord Locating driver system 25 be shown schematically as a chest.Complicated or three-dimensional (3D) object is by progressively shaping simultaneously And cool down molten bath 29 and formed in layer 24 on the base plate 20.Form molten bath 29 to melt by appropriate by using electron beam 14 The consumable silk 16 that metal (such as aluminium or titanium) is formed.Consumable silk 16 is supplied from wire feeder 18 to molten bath, wire feeder 18 is typically Other suitable conveying mechanisms including bobbin or with controlled speed.

Device 10 shown in Fig. 1 and Fig. 2 also includes closed loop controller (C) 30, and it has main frame 32 and is suitable to control makes The algorithm 100 of EBFFF process is carried out with device 10.Controller 30 is electrically connected or communicated with main process task controller 34, main process task Controller 34 be suitable to by necessary order send to electron beam gun 12, wire feeder 18 and positioning substrate 22 and rifle 12 it is any needed for Motor (not shown).Controller 30 is generated and sends one group of |input paramete 11, as being set forth below, this group input ginseng Number 11 changes final control parameter 11F.

In one embodiment when being melted to more than about 1600 degree by electron beam 14, consumable silk 16 is according to one group of design Data 19 (such as CAD (CAD) data or other 3D design documents) are accurately progressively deposited on pantostrat In.By this way, 3D structure members or other complex objects can be created by increasing material mode, without die casting or Molding.

Fig. 3 is illustrated for example computer system 200 in one or more embodiments, it is thus evident that for predicting Incident deformation in the workpiece manufactured by device 10, and for providing data to controller 30 in various embodiments So that change can be introduced in workpiece to compensate the deformation of the prediction.Computer system includes one or more processors, such as Processor 202, processor 202 is connected to inside computer system communication bus 204.

Computer system 200 also includes main storage 206, preferred random access memory, additionally it is possible to including auxiliary storage Device 208.Additional storage 208 can include such as one or more hard disk drives 210 and/or one or more removable deposit Storage driver 212.Removable storage drive 212 is read out and/or writes shifting from mobile memory cell 214 in a known manner Dynamic memory cell 214.As it will be realized, mobile memory cell 214 includes the available storage medium of computer, it will be calculated Machine software and/or data storage are wherein.

In alternative embodiments, additional storage 208 can include other likes, and it is used to allow computer journey Sequence or other instructions are loaded in computer system 200.This part can include for example moving memory cell 216 and interface 218.Their example can include the socket of removable memory chip, EPROM, USB flash memory etc., and association or its His removable storage unit and interface, they allow softwares and data to be transferred to department of computer science from removable storage unit 216 System 200.Computer system 200 also includes being connected to the communication interface 220 of bus 204.Communication interface can also include I/O interfaces 222, it provides access of the computer system 200 to monitor, keypad, mouse, printer, scanner, draught machine etc..

Main storage 206 can be stored in the computer program for causing execution various functions in series of instructions form And/or in the application module 224 in additional storage 208.Computer program can also be received via communication interface 220.When holding During row, this computer program can make computer system 200 perform feature and provide function described herein.Especially, when During execution, computer program can make processor 202 perform feature described herein.

In one embodiment, application module 224 is configured to before manufacturing by increasing material manufacturing and make workpiece The thermomechanical model of finite element during making carries out finite element analysis, to predict workpiece in shape distortion and/or residual stress send out Exhibition.In one or more embodiments, application module 224 is further adapted for determining and carrying out workpiece before manufacture or during manufacture Change compensating the deformation of the prediction.In addition, module 224 stores the thermomechanical model of finite element of the workpiece to be manufactured.

Fig. 4 is the data, limited to the data by the application of module 224 being input in the module 224 of computer system 200 The signal of meta analysis (FEA) model and the predicted stresses generated by module 224 and deformation data and workpiece change data Figure.Depending on before increasing material manufacturing is processed, period and at the end of workpiece 3D geometries 248 input, carry out prediction meanss The shape distortion in workpiece and/or residual stress development manufactured by 10.Except geometry input 250, provide to module 224 The parameter of the various manufacturing steps of restriction and condition 252.

Then carry out finite element analysis and to determine using FEA model 254 possibly be present at workpiece during manufacture is processed In predicted stresses and deformation 256.FEA model 254 includes a series of units, and referred on behalf of 260 to 268, they can make FEA model 254 considers the correlated phenomena on workpiece.Model unit 260 to 268 can make instantaneous thermo-mechanical analysis mould Draw up the complete moulding of the workpiece to be performed during all normal phases of physics moulding.In one or more embodiments In, these normal phases include the preheating substrate, deposit by electron beam or the material of other heat/energy source fusing, making Cooling down workpiece and its deformation after unloading after mechanical constraint has been released after type.

Prediction of distortion 256 is compared with input geometry.Indicate prediction of distortion in pre- constant volume if comparing 258 In difference, then it is input into geometry 250 and is output 262 to controller 30.But, if prediction of distortion is more than predetermined tolerance, will Input geometry 250 is updated using change 260, to guarantee that manufactured workpiece includes the compensation for prediction of distortion.

Using multinode solid element to before manufacture, manufacture during and manufacture after geometry carry out grid draw Point.Fig. 5 and Fig. 6 show the He of example 300 of the T-shaped geometry that stress and strain model is carried out using linear 8 node entities unit 302.Although the quantity of unit can be high as needs, typically, each workpiece can have about 10,000 to 30,000 units.In the case of there are monosymmetric workpiece and the shape handles, it is only necessary to which the half of workpiece is modeled (Fig. 5).But, when being not the case, then by the whole geometry models (Fig. 6) of workpiece.Workpiece moulding it Front and in the basal plate preheating stage, the unit for merely comprising the 3D geometries of substrate is active.It is right when workpiece moulding is carried out The unit in wall should be progressively activated in the material of deposition.At any time, still sluggish unit to using FEA model 254 by The model that module 224 is performed is calculated and not worked.

In one embodiment of the invention, FEA model 254 includes following model unit：

Heat transmission unit

Heat transmission unit is used for the heat conduction model in substrate and deposition materials.Heat conduction in substrate and deposition materials Rate and specific heat are that have temperature dependent.Fig. 7 and Fig. 8 respectively illustrate the temperature dependent exemplary view of the two attributes 304 and 306.The data for these curve maps can be compiled from multiple publicly available resources.Manufactured using titanium alloy In the case of workpiece, one this to be suitably referenced as：" material properties handbook：Titanium or titanium alloy ", edits R.Boyer, G.Welsch and E.W.Collings, ASM are international, material depot, Ohio, USA, 1994.

Heat transfer unit

Heat transfer unit is used for from workpiece to outside heat transfer model.In one embodiment, heat transfer unit According to the heat radiation of workpiece by heat transfer model.Alternatively, heat transfer unit can extraly will according to the heat transfer of workpiece Heat transfer model.

Following radiation condition can be used by the radiation model of workpiece：

Wherein, q is heat flux, and ε is surface emissivity, and σ is Stefan-Boltzmann constant.It should be noted that at this slightly In formula afterwards, temperature is absolute temperature (K).The value of h and ε can be adjusted to match experimental result.Work is being manufactured by titanium alloy In the case of part, it has been found that the representative value for these parameters is h ≈ 20W/ (m²) and ε ≈ 0.7 K.Although sometimes can The value is adjusted preferably to match experimental result, but the value that usually can be used is T_amb=303.15K (30 DEG C).

Can be according to below equation by heat conduction model：

Q=h (T-T_amb)

Wherein, q is heat flux, and T is temperature, T_ambIt is environment temperature；Or by using radiation condition by heat conduction model Change.

Elastic deformation unit

The material properties included in the model unit include Young's modulus, Poisson's ratio and thermal coefficient of expansion.It is hypothesized each To the attribute of the same sex.In one or more embodiments, the Poisson's ratio for adopting is for v=0.3.Young's modulus and thermal coefficient of expansion temperature Degree both has temperature dependent, and value can be obtained from publicly available document, all as noted above handbooks.This A little Attribute Relatives are illustrated in Fig. 9 and Figure 10 in the example graph 308 and 310 of temperature.Although obtainable for Young's modulus Data be used to being up to about the temperature of 1073K (800 DEG C), but it can be inferred that for the data available of higher temperature, and Assume that Young's modulus is zero (0) when workpiece material reaches liquidus temperature.

Yield behavior unit

In various embodiments, yield behavior unit follows von mises criterion, and von mises criterion is proposed：When Material starts surrender when two deviatoric stress invariants reach critical value.Initially, surrender is described using Johnson-Cook models Progress, but, applicant have determined that, in high temperature, Johnson-Cook models be not suitable for describe Ti-6Al-4V alloys with And the yield behavior of other metal alloys.And, the sensitivity analysis that applicant is carried out is indicated, is made for metal alloy Deform the impact to strain hardening and strain rate after type can ignore that, it is simpler used in FEA model 254 so as to allow By rule of thumb temperature correlation flow stress.Therefore, yield behavior unit follow the temperature dependent for deriving by rule of thumb flowing should Force data, exemplary view 312 just as illustrated in Figure 11.

Material sedimentation unit

There are many complex fluid flowings occurred during material is deposited and be heat-treated.In the preparation that applicant is carried out In work, the modelling of the deposition materials of fusing is included in the model unit.But, it has been determined that go out, can adopt simpler It is single, less to calculate the strategy of intensity, and do not lose the degree of accuracy.The modelling strategy that material sedimentation unit is adopted now is, in liquid Under liquidus temperature (1923K (1650 DEG C)) or slightly higher than liquidus temperature is using a small amount of overheated deposition modeling by material. Height and width, the sedimentation rate and direction of each sedimentary are reasonably set to the actual characteristic of close moulding.

Solidification unit

When uniformly occurring in solidus temperature 1878K (1605 DEG C) to the 45K scopes between liquidus curve 1923K (1650 DEG C) When by the SOLIDIFICATION MODEL of deposited metal.In this example embodiment latent heat is 269.5kJ/kg.

Alternatively, material sedimentation unit by material it is deposition modeling with simulation material because with known power level energy The fusing that amount/thermal source is carried out.

Basal plate preheating unit

In one or more embodiments, electron beam can be to pre- hot substrate.When the mobile volumetric sources in substrate This can be modeled.At any time, distributed using volume input, the thermal source can be modeled as elliptic region, volume Input distribution is integrated into the ratio heat flux from electron beam.Move corresponding to the motion of electron beam in the oval source.Given body Accumulated heat amount is input into (power of per unit volume)：

Wherein, Q=η P, and P is nominal power input, η is efficiency, and energy is transferred to workpiece with the efficiency.Parameter f_f, f_r By being given below：

Thereby it is ensured that the heat input integrated in whole elliptic region is Q.

Give an example, the particular value that applicant has used in the modelling of T-shaped workpiece is：

● a=7.1mm, b=4mm, c_f=3mm, c_r=5.9mm

● η=0.7

The speed in power P and source is specified by modeling parameters.

During physics or actual moulding, substrate is typically placed in certain fixing device, for mechanical support with And constraint purpose.The fixing device acts also as hot cold (the thermal chill) of the workpiece for just manufacturing.Applicant is previously bright Really modeled and the fixing device is included to calculate a part for finite element analysis model 254.But, it is bad that it has Gesture is the run time for dramatically increasing size and model.Based on the reason, FEA model 254 adopts simpler method, thus The mechanical attributes of fixing device were similar to using showing to the simpler T-shaped base case geometry for being illustrated in Fig. 5 and Fig. 6 Formula is constrained.Then the refrigeration effect of fixing device is close to by effective heat transfer coefficient.

The characteristic of data 252 of manufacturing step/condition can also limit multiple setup parameters, applicant have determined that going out these Parameter has on the shape distortion and residual stress development during manufacture and after manufacture in workpiece to be affected.These parameter bags Include：

1. the preheating level of the prebasal plate of moulding.

2. from the heat transfer of workpiece during construction.This includes that investigation is sensitive for external heat transfer boundary condition parameter Property, and the degree of internal heat transfer is carried out to fixing device particularly by gripping features.

3. deposition velocity and per layer deposition between cool time.

4. deformation-non-" straight " part after pre-bend substrate can be realized to compensate moulding.

5. the order of moulding in each layer.

Manufacturing step/condition 254 can extraly possess following manufacturing step, it has been found that each following manufacturing step energy Enough make generation further minimum heat losses during manufacture, therefore send out generation shape distortion within the workpiece and/or residual stress Exhibition is minimized：

● by during the deposition of continuous material not cooling down workpiece come make during one or more fabrication stages come From substrate and the further minimum heat losses of deposition materials.For example, it has been found that it is desirable that, between the deposition of the pantostrat of material The mean temperature for preventing workpiece declines 10%.

● made by workpiece applying thermal insulation during manufacture during one or more fabrication stages from substrate and The further minimum heat losses of deposition materials.By applying heat-insulating material between substrate and workbench, can be by adiabatic application to work Part, substrate is supported during manufacture by workbench.

● made by applying radiation reflective to workpiece during one or more fabrication stages from substrate and deposition material The further minimum heat losses of material.

And, manufacturing step/condition 254 can include it is found by the applicant that parameter, so as to pass through when cooling is manufactured Control is to keep the reduction to the clamping force of support works platform to control in one or more fabrication stages substrate during workpiece The mechanical boundary conditions of period, so as to minimize or avoid the critical residual stress development in workpiece, to minimize or Crack prevention is formed.

From the above it is readily apparent that successfully developing the modeling technique for considering many physical phenomenons to simulate EBFFF process.The forecasting tool is carried to the progress of temperature in whole workpiece during moulding and after moulding and internal stress distribution Opinion is supplied, and opinion has been provided to the progress of final structural strain's and residual stress.

The modeling technique is effective to multiple T-shaped parts and cross shape part.Between model prediction and experiment measurement Uniformity be good in terms of initial development, and be excellent after modelling instrument is by accurate adjustment, in design and make The stage of making gives the predictive ability of instrument with the reliability of height.

Model effectively to perform a series of experiment of virtual designs, how to assess structural strain's by various operations Parameter and condition, moulding path, preheating or the impact of preform substrate and combinations thereof effect.

Model shows, deform after moulding it is extremely sensitive in energy input (beam power) and thermal boundary condition, such as Time interval between the fin effect of fixture and each pass (cooling).

For T-shaped part, it has been found that the substrate of pre-bend is effective Transfiguration Management method, can be almost complete The deformation of full compensation simple shape.

Simply fixture thermal insulation is predicted to be can significantly reduce deformation, it has been shown that experimental measurements can be real Now reduce by 34%.

By basal plate preheating but this forecast model of substrate is not kept not to be highly effective to reducing deformation during moulding. Halve with the fixture of thermal insulation and by moulding speed with reference to preheating (500 DEG C), predict that this can reduce deformation 39%, only in edge Higher than not preheating but have the situation of adiabatic fixture.Additionally, basal plate preheating to this high-temperature is introduced into operating difficulties, to manufacturer For be not preferred selection.

Forecasting tool can estimate assume operating condition effect, such as very high preheating temperature, and to moulding after Deformation and the combined effect of residual stress, although they are currently it appears that be unpractical.

The modeling technique and forecasting tool of exploitation can extend to other increasing material manufacturings and process, especially with nickel, aluminium And the layer of titanium and metal alloy is manufacturing the process of workpiece.

Planning of experiments

Below explanation be related to regard to using the increasing material manufacturing T-shaped of titanium alloy and the experimental design of cross shape workpiece with test Card, it is to be understood that the embodiment of description can be in the increasing material system using other metals, metal alloy and similar material Use under the background made.

The exploitation and checking of the forecasting tool of the deformation and residual stress development during for moulding and after moulding Simulation is mainly to use what appropriate processing parameter was performed using general non linear finite element analysis solver.In the starting stage In, make great efforts also to include stress and strain model technology to create the FEM model of description deposition path.It has been found that fixed for the concrete application What solver processed was a need for.

Two different companies are transferred to for the selected moulding for proving part of model calibration and checking.T-shaped part will Ask and only deposit in the side of substrate, and cross shape part requirement is deposited in the both sides of substrate.This is by using roll-over table reality Existing.Deformation measurement is performed using 3D scanners.Residual stress measurement is performed to selected moulding by neutron diffraction techniques.

Then output model result is compared with experiment residual stress and deformation data, for model calibration and Verifying purpose.Model result provide to the temperature during increasing material manufacturing and after increasing material manufacturing in molded part, deformation with And the understanding of the progress of stress.Then various tool paths and process are investigated using model in prognostic experiment design pattern Impact of the parameter to (after manufacture) part distortion and residual stress.

Company A carries out moulding to multiple side T-shaped and both sides cross shape part, and company B is to four sides T-shaped portion Part carries out moulding.Substrate Ti-6Al-4V plates are long for 2 feet (600mm), and 4 inches (100mm) is wide, and 0.5 inch (12.5mm) is thick. 2 inches (51mm) height is deposited as, and including single pass welding, 0.472 inch (12mm) is wide.(a) and (b) of Figure 12 is respectively illustrated The exemplary diagram 314 and 318 of T-shaped and cross shape part.T-shaped part requirement is only deposited in the side of substrate, and cross Shaped member requires to be deposited in the both sides of substrate.This is realized by using roll-over table.Table below 1 shows two skills The EBFFF processing parameters that art supplier is used for production moulding.

Form 1

The substrate for using is clamped arranges the thermal boundary condition affected dearly for moulding.Company A and B use different folders Tight arrangement.Company A is also using the different clamping conditions for side and both sides moulding.For side moulding, they use tool There is the turntable of steel facing, and be clamped along zig via aluminium bar at four points.For bilateral moulding, company A is using aluminium head and tail frame " roll-over table " come around its center line rotary part.Aluminium bar and spring-loaded clips are used along its long size Tool carrys out clamping substrate, while each fixture is loaded as 500lbs based on spring constant information.Two thermocouples are attached at substrate Each end, near moulding monitoring thermal history during moulding.In company B, fixed plate by AA5083 aluminium alloys process with Exemplar is kept while processing.The fixing device is maintained at old on the X-Y CNC platforms being mounted in vacuum chamber again On vice.Using five thermocouples, two thermocouples therein are used respectively in the initial and end of moulding, three therein Thermocouple is used at the center of moulding.

Various moulding are scanned by using portable 3D scanners and implements deformation measurement.Term " deformation " used herein As the average of two vertical ranges measured between the raising edges of central point to substrate basis.

In one plane residual stress measurement is carried out using neutron diffraction techniques at center along the longitudinal direction of substrate. Because titanium provides weaker diffracted signal, neutron measurement tends to tediously long.In obtainable beam time, along three directions 318, 320 and 322 (longitudinally, laterally and normal direction) measured, such as along each of part 324 shown in (c) of Figure 13 (a) to Figure 13 Plant point.

Figure 13 (a) illustrates normal direction residual stress measurement planning chart, wherein, neutron comes from primary cleft (right side), leads to Cross visible secondary interstice behind sample to collect the neutron of diffraction.(b) and (c) of Figure 13 respectively illustrates the He of curve map 326 328, they illustrate the point of the residual stress measurement of the side T junction of the side T junction and company B for company A Position.

Model specification

In order to perform model checking and calibration, applicant is required to a certain amount of actual survey compared with model prediction Amount.In order to the purpose uses three kinds of measurements：

1. using the final deformation of portable 3D scanners measurement.Once this is related to workpiece and has cooled down to room temperature and owns Mechanical constraint has been released from, and in the end of moulding the relative vertical displacement of substrate is measured.

2. final residual stress is measured.These measurements are carried out using neutron diffraction.

3. continuous temperature data during moulding.For the structure of company B, five thermocouple points are welded in the rule on substrate Positioning puts place, and temperature data is continuously collected in moulding and during the cooling cycle.As, as mentioned previously, it is also public from some Limit temperature data are collected in the moulding of department A；But, due to the weaker thermo-contact between thermocouple and substrate, it is found that this is not Reliably.

Because model some setting and processing parameter be uncertain, be estimated, assessment models prediction for How sensitive the change of these parameters have.The instruction that the analysis of the type is given is that actual moulding can be how sensitive to these parameters, And some opinions of the potential method to managing final deformation are given in like fashion.Therefore this calculating Code's Sensitivity also rises The effect of virtual experimental.Some setup parameters of investigation include following parameter：

1. before moulding pre- hot substrate level.

2. from the heat transfer of workpiece during moulding.This includes that investigation is sensitive for external heat transfer boundary condition parameter Property, and the degree of internal heat transfer is carried out to fixing device particularly by gripping features.

3. cool time between deposition velocity and per layer of deposition.

4. deformation-non-" straight " part after pre-bend substrate can be realized to compensate moulding.

5. the order of moulding in each layer.

Below table 2 is given for company's A moulding Code's Sensitivity for being carried out and the details for testing virtual design.Relate to And base case be described in below table 3.

Form 2

Form 3

Experimental result

The details of the experiment moulding of company A and company B productions is shown in below table 4.Amount to, 20 moulding are by company A is produced, including 5 bilateral moulding, and 4 side T-shaped moulding are produced by company B.Deformation measurement is also illustrated that in form 3.1 As a result.Although nominally company A and company B are produced for the four of each situation using identical modeling parameters and condition Individual moulding, but it can be seen that there are some dispersions in the deformation of measurement.It is also obvious that company's B moulding is displayed in measurement Higher deformation and more high dispersive in deformation.Selected sample undergoes the stress elimination heat treatment of standard；As seeing Form 4, this is considered as causes average deformation somewhat to increase, but it is possible that this is in and the deformation survey carried out by 3D scannings In the experiment dispersion of amount result association.

Form 4

Model is verified

Figure 14 shows three " thermal maps " 400 to 404, and they are illustrated when (a) completes moulding deposition, (b) in chamber In be cooled to less than 100 DEG C afterwards, and (c) from fixture release sample after, the progress of von mises stress.Work as sample During cooling and still while being clamped, it was observed that stress is substantially increased, at the substrate top surface of neighbouring deposition end Obvious very high stress concentration.But, when release clip, stress reduces and and occurs deforming.

Figure 15 is shown by modeling predicting and illustrate and deform and illustrate after the moulding in " thermal map " 406 The comparison of the experiment moulding in image 408.The model prediction final deformation of close 12mm, and 3D scanning survey results show For the deformation of the 5.33mm of correspondence sample (F-7053-A in form 4).This difference is mainly due to Johnson-Cook moulds Type can not suitably describe Ti-4Al-6V alloys yield behavior at high temperature.

Figure 16 shows three " thermal maps " 410 to 414, and they illustrate (a) when moulding is completed, and (b) are less than being cooled to 100 DEG C afterwards, and (c) from fixture after sample is discharged, the predicted evolution of von mises stress.When sample is cooled down again It is secondary significantly at the substrate surfaces of neighbouring two depositions end, it was observed that stress is substantially increased.But, when in side moulding In the case of from fixture discharge sample when do not occur stress reduce.

Figure 17 show by model prediction and deformation is shown after the moulding in " thermal map " and is tested in moulding corresponding The comparison deformed after moulding that is measuring and illustrating in image 418.The deformation of prediction is very consistent with experiment, and they are showd that Very can be with the deformation (being less than 0.5mm) of negligible amount.As mentioned above, both sides moulding causes to be close in contrary deposition and puts down The residual stress of weighing apparatus, this helps to maintain and deform after moulding minimum.Double-sided deposition technology almost eliminated and deform after moulding, but Residual stress will be still higher.

As mentioned above, although in principle experimental result is consistent with modelling, but be highly desirable to improve prediction the degree of accuracy. Therefore, begin attempt to strengthen modelling instrument from the middle ten days in 2013.In the modeled process, heat analysis and mechanical analysis are every Associate in individual step.

It is because the heat analysis adopted in here work are well-verified and effective to another purpose experiment, therefore Attention focusing is on the material model for using.Figure 18 is that figure illustrates 420, and it is illustrated based on Johnson-Cook model phases For the experimental data collected, as the curve map of the flow stress of the function of temperature.Clearly, Johnson-Cook models are not The yield behavior of Ti-6Al-4V at high temperature can be described.

Figure 19 illustrates " thermal map " 422 and " thermal map " 424 and 426, and " thermal map " 422 is shown and measured using neutron diffraction Longitudinal residual stress, " thermal map " 424 and 426 show based on Johnson-Cook models and update material model and predicted Longitudinal residual stress.It is seen that, in terms of stress distribution and value, drawn based on the prediction of Johnson-Cook models Residual stress is significantly higher than measurement, and is based on and updates the prediction of material model and measure extraordinary consistent.

In order to veritify the modelling instrument of accurate adjustment, simulation is performed to the experiment moulding with adiabatic fixture, this guarantees more true Determine thermal boundary condition.Figure 20 includes image 428 and " thermal map " 430 and 432, and image 428 is shown from experiment moulding measurement Deform after moulding, " thermal map " 430 and 432 is shown and deformed after the moulding predicted that modelling is realized.It is based on The deformation that Johnson-Cook models and renewal material model are predicted is respectively 8.45mm and 3.07mm.3D scanning survey results Show that the average deformation for 4 test specimens (being shown in Table lattice 4) is 3.33mm.Model and based on renewal material model Comparison between the prediction that experiment confirms substantially is improved in the degree of accuracy, so as to increased the reliability of predictive models instrument, Especially in the design phase.

Now, due to the model for updating cannot be used, experiment virtual design is performed using Johnson-Cook models.Profit The modelling instrument developed with us has virtually investigated various modeling schemes and (has such as changed processing parameter, moulding order, moulding Speed etc. (form 1)) to after moulding deform impact.Fig. 3 .18 outline the result for being obtained from experiment virtual design, compared to Corresponding to " real " baseline case of experiment moulding, using aluminium alloy fixture in position.

It is by only that fixture is adiabatic and realize, while have more having that deformation significantly reduces 30.1 percent after moulding The method of effect, such as can be completely eliminated after moulding using the substrate of pre-bend and be deformed.Other " limit " methods, such as actively add Hot substrate to the temperature higher than 1300K shows substantially reducing for deformation, but violates metallurgical constraint, hardly can implement.

Figure 21 shows that the figure of the change of the deformation of the selected experimental design result for considering to veritify for experiment is illustrated 434.Due to company A postpone make the pre- hot substrate of equipment and arrange constraint, therefore be unable to sample plot checking for basal plate preheating, The reduction of the deformation that the combined effect of fixture thermal insulation and half baseline construction speed is predicted.

Four experimental side moulding with adiabatic (ceramics) fixture are subsequently produced by company A, show average moulding After be deformed into 3.33mm (form 4).Compared to for be clamped to via aluminium alloy rod the sample of fixing device 5.03mm it is flat Deform after moulding, realize after moulding that deformation reduces by percent 34 using ceramic thermal insulation fixture, higher than by modelling prediction (27.7 percent).The difference can be attributed to the restriction of previously mentioned Johnson-Cook models.

Figure 22 shows " thermal map " 436 and 438, and they illustrate temperature and the T for the construction on pre-bend substrate The von mises stress distribution that shape part is predicted at the end of moulding.Figure 23 shows " thermal map " 440 and 442, their figures Illustrate that (a) is being cooled to less than 100 DEG C afterwards and (b) Feng meter Sai after release clip in the moulding of pre-bend substrate The predicted evolution of this stress.

The modelling of applicant is predicted, and deformation after moulding should straighten pre-bend substrate, however, experimentation have shown that situation is not It is such.In these experiments, substrate be folded to by pre-bending along the direction contrary with expected deformation～value of 5mm is (that is, along indulging To direction in a substrate between there is maximum deflection 5mm at plane).This corresponds to what is observed in the T-shaped moulding of baseline side Deform (about 5mm) after 100% moulding, wherein, substrate is clamped by aluminium bar.Subsequent experimental is veritified and shown, what is measured averagely makes Deformation after type remains as -1.76mm, and this indicates that the pre-bend value of -5mm is excessive.It should be noted that the model is base In being intended to excessively to predict the Johnson-Cook material models that deform after moulding.Based on the pre-bend value that Modelling results are proposed Therefore become at this moment.

Figure 24 show by modelling predict and " thermal map " 444 shown in moulding after deform with image 446 shown in it is right The comparison between the measurement deformation of moulding should be tested.As discussed earlier, although model prediction go out deformation should close zero, but It is that pre-bend is not compensated completely during experiment moulding.

Figure 25 illustrates the example of the more complicated geometry 450 of geometry than being illustrated in Fig. 5 and Fig. 6.

Figure 26 shows " thermal map " 452 and 454, and they are illustrated respectively by modeling predicted geometry 450 Moulding after the isometric view that deforms and side view, Figure 27 shows " thermal map " 456 and 458, and they are illustrated respectively in chamber In be cooled to less than 100 DEG C the isometric view and side view of deformation afterwards by the predicted geometry 450 of modelling, figure 28 show " thermal map " 460 and 462, and they illustrate passing through to model geometry from after fixture release workpiece respectively The isometric view and side view of 450 deformations predicted." thermal map " 452 to 462 shown in Figure 26 to Figure 28 is the example of prediction, Wherein, before manufacture or manufacture during not by compensation prediction deform change introduce workpiece.

Figure 29 to Figure 31 show correspondence " thermal map ", they illustrate before manufacture or manufacture during when change is introduced into With the prediction of distortion during deformation of compensation prediction during workpiece.Figure 29 shows " thermal map " 464 and 466, and they illustrate respectively logical The isometric view and side view deformed after the moulding of the predicted geometry 450 of modelling is crossed, Figure 30 shows and is being cooled to 100 DEG C are shown afterwards by " thermal map " 468, Figure 31 of the isometric views of the deformation of the predicted geometry 450 of modelling " thermal map " 470 and 472, they are illustrated after workpiece is discharged from fixture by the predicted geometry 450 of modelling The isometric view and side view of deformation.

In this example embodiment, the deformation of compensation change is performed using following steps：

A) using the reference moulding shown in conventional tool placement model/analysis Figure 25, to predict heat during manufacture The progress of distribution, deformation and stress；

B) the first time repetition of modelling/deformation-compensated moulding of analysis, wherein, in this case, artificially constrain whole Substrate is in case vertical displacement (keeping flat), the heat distribution, deformation, stress and reaction with prediction at all clamping points The progress of power；

C) (a kind of mode is realized being applied to substrate to apply deformation-compensated change to substrate using the deformation from step b) predictions Plus reverse vertical deformation, the value of the deformation is 1/2 of the prediction of distortion in step b or 3/4), and then modelling/analysis becomes Second repetition of shape compensation moulding, wherein, in this case, whole substrate is artificially constrained against vertical displacement, to predict The progress of heat distribution, deformation, stress and reaction force at clamping point；And

D) repeat step c) is until realizing moulding tolerance.

It is visible such as from Figure 29 to Figure 31, when before manufacture or during manufacture change being introduced into workpiece compensating Figure 26 extremely In Figure 28 during visible prediction of distortion, prediction of distortion is significantly reduced in all stages of manufacture.

The reduction of deformation is confirmed in Figure 32, Figure 32 illustrates " thermal map " 474, it illustrating mould when do not introduce deformation-compensated change The deformation of type prediction, illustrates the image 476 of manufactured workpiece, illustrates " thermal map " 478, and it is illustrated when deformation-compensated change is introduced into The deformation of model prediction during model.

Claims (43)

1. a kind of method of the minimizing deformation for making workpiece, methods described comprises the steps：

In computer systems, to the finite element heat during being manufactured by increasing material manufacturing and after manufacture of the workpiece Mechanical model carries out finite element analysis to predict the shape distortion and residual stress development of workpiece, wherein, the manufacture includes The manufacturing step multilayer material melted by thermal source being deposited on along deposition path on substrate；And

Before manufacture or during manufacture change is introduced into the deformation that the workpiece is arrived with compensation prediction.

2. method according to claim 1, wherein, the manufacture further include in following manufacturing step or It is multiple：The substrate is preheated, the workpiece is cooled down, and subsequently releases the mechanical constraint on the workpiece.

3. method according to claim 2, wherein, the thermal source include it is following in one or more：Electron beam, weldering Arc, plasma arc and laser beam.

4. according to method in any one of the preceding claims wherein, wherein, geometry to the substrate and described heavy One of product path or many persons are modified.

5. according to method in any one of the preceding claims wherein, wherein, the model is included for by the substrate and institute State the heat transmission unit of the heat conduction model in deposition materials.

6. according to method in any one of the preceding claims wherein, wherein, the model include for will from the workpiece to The heat transfer unit of outside heat transfer model.

7. method according to claim 6, wherein, the heat transfer unit is according to the heat radiation of the workpiece by heat transfer Modelling.

8. method according to claim 7, wherein, the heat transfer unit is according to below equation by heat transfer model：

$q=\mathrm{\ϵ}\mathrm{\σ}(T^4-T_{amb}^4)$

Wherein, q is heat flux, and T is temperature, T_ambIt is environment temperature, ε is surface emissivity, and σ is Stefan-Boltzmann constant.

9. the method according to claim 7 or 8, wherein, the heat transfer unit is extraly passed according to the heat of the workpiece Lead heat transfer model.

10. method according to claim 9, wherein, the heat transfer unit is according to below equation by heat transfer model：

Q=h (T-T=T_amb)

Wherein, q is the heat flux, and T is the temperature, T_ambIt is the environment temperature.

11. according to method in any one of the preceding claims wherein, wherein, the model includes using Hooke's law, described The elastic deformation unit of the Young's modulus, Poisson's ratio and thermal coefficient of expansion of material.

12. according to method in any one of the preceding claims wherein, wherein, the model includes following von mises surrender The yield behavior unit of criterion.

13. according to method in any one of the preceding claims wherein, wherein, the model includes yield behavior unit, described Yield behavior unit follows the flow stress data of the temperature dependent for deriving by rule of thumb.

14. according to method in any one of the preceding claims wherein, wherein, the model includes material sedimentation unit, wherein, In liquidus temperature or slightly higher than described liquidus temperature is using a small amount of overheated by the deposition modeling of the material.

15. according to method in any one of the preceding claims wherein, wherein, the model includes solidification unit.

16. methods according to any one of claim 1 to 13, wherein, the model includes material sedimentation unit, its In, the material carried out with melting the material by applying energy/thermal source is deposition modeling.

17. further include following steps according to method in any one of the preceding claims wherein, methods described：Using from The stress analysis information of the finite element analysis come recognize local stress increase, using the thermal source one or more manufacture Need to mitigate the local stress increase during stage.

18. further include following steps according to method in any one of the preceding claims wherein, methods described：By in material The workpiece is not cooled down between the deposition of the pantostrat of material, is made during one or more fabrication stages from the substrate and institute State the further minimum heat losses of deposition materials.

19. methods according to claim 18, wherein, the flat of the workpiece is prevented between the deposition of the pantostrat of material Temperature drop 10%.

20. further include following steps according to method in any one of the preceding claims wherein, methods described：By in system Make the workpiece adiabatic during making and after manufacture, make during one or more fabrication stages from the substrate and described heavy The further minimum heat losses of product material.

21. further include following steps according to method in any one of the preceding claims wherein, methods described：By to institute State workpiece and apply radiation reflective, make during one or more fabrication stages from the substrate and the heat waste of the deposition materials Lose and minimize.

22. further include following steps according to method in any one of the preceding claims wherein, methods described：By heavy The substrate is preheated before the product material, the thermal gradient between the workpiece and the substrate is minimized.

23. further include following steps according to method in any one of the preceding claims wherein, methods described：By basis With part cooling, the limit stress control clamping force of change reduces controlling during one or more fabrication stages Mechanical boundary conditions, are formed or other manufacturing defect with minimizing either Crack prevention.

24. according to method in any one of the preceding claims wherein, wherein, the material is metal or metal alloy.

25. methods according to claim 24, wherein, the metal alloy includes titanium, aluminium, nickel, vanadium, tantalum, copper, scandium, boron With any one of magnesium or various.

26. methods according to claim 25, wherein, the metal alloy is Titanium alloy Ti-6Al-4V.

A kind of 27. computer implemented methods of the deformation of prediction workpiece, methods described comprises the steps：

In computer systems, to the finite element heat during being manufactured by increasing material manufacturing and after manufacture of the workpiece Mechanical model carries out finite element analysis to predict the shape distortion and residual stress development of workpiece, wherein, the manufacture includes The manufacturing step multiple layers of the material melted by thermal source being deposited on along deposition path on substrate.

28. computer implemented methods according to claim 27, wherein, the manufacture further includes following manufacturing step In one or more：The substrate is preheated, the workpiece is cooled down, and subsequently releases the mechanical constraint on the workpiece.

29. computer implemented methods according to any one of claim 27 to 28, wherein, the model includes heat transfer Unit, the heat transmission unit is used for the heat conduction model in the substrate and the deposition materials.

30. computer implemented methods according to any one of claim 27 to 29, wherein, the model includes heat transfer Unit, the heat transfer unit is used for from the workpiece to outside heat transfer model.

31. computer implemented methods according to claim 30, wherein, heat of the heat transfer unit according to the workpiece Radiate heat transfer model.

32. computer implemented methods according to claim 31, wherein, the heat transfer unit is according to below equation by heat TRANSFER MODEL：

$q=\mathrm{\ϵ}\mathrm{\σ}(T^4-T_{amb}^4)$

Wherein, q is heat flux, and T is temperature, and T_amb is environment temperature, and ε is surface emissivity, and σ is that Stefan-Boltzmann is normal Number.

33. computer implemented methods according to claim 31 or 32, wherein, the heat transfer unit is extraly according to institute The heat transfer of workpiece is stated by heat transfer model.

34. computer implemented methods according to claim 33, wherein, the heat transfer unit is according to below equation by heat TRANSFER MODEL：

Q=h (T-T_amb)

Wherein, q is the heat flux, and T is the temperature, T_ambIt is environment temperature.

35. computer implemented methods according to any one of claim 27 to 34, wherein, the model is included using recklessly The elastic deformation unit of gram law, the Young's modulus of the material, Poisson's ratio and thermal coefficient of expansion.

36. computer implemented methods according to any one of claim 27 to 35, wherein, the model includes following The yield behavior unit of von mises yield criterion.

37. computer implemented methods according to any one of claim 27 to 36, wherein, the model includes surrender row For unit, the yield behavior unit follows the flow stress data of the temperature dependent for deriving by rule of thumb.

38. computer implemented methods according to any one of claim 27 to 37, wherein, the model is heavy including material Product unit, wherein, in the liquidus temperature or slightly higher than described liquidus temperature is using a small amount of overheated by the material It is deposition modeling.

39. computer implemented methods according to any one of claim 27 to 38, wherein, the model includes that solidification is single Unit.

40. computer implemented methods according to any one of claim 27 to 37, wherein, the model is heavy including material Product unit, wherein, the material carried out with melting the material by applying energy/thermal source is deposition modeling.

A kind of 41. non-transient computer-readable mediums, the non-transient computer-readable medium is carried out to series of instructions Coding is so that method of the computing device according to any one of claim 27 to 40.

A kind of 42. increasing material manufacturing devices, the increasing material manufacturing device includes：

Thermal source；Wire feeder；Workbench, the workbench is used for supporting substrate, and material deposition is carried out on the substrate；Moving machine Structure, the travel mechanism is used to provide the relative movement of the thermal source, wire feeder and workbench；And vacuum chamber, it is described true Empty room closes the thermal source, wire feeder, workbench and travel mechanism；

Control device, the control device is used to control the operation of the thermal source, wire feeder, workbench and travel mechanism；With And

Computer system, the computer system includes：

Main storage, the main storage is used for storage for the computer-readable code of Finite Element Method ＆ Its Application module；

At least one processor, at least one processor is attached to the main storage, and at least one processor is held The computer-readable code in the row main storage so that the application module to the workpiece before manufacture and system The thermomechanical model of finite element during making carries out finite element analysis to predict the shape distortion and/or residual stress development of workpiece, And at least one processor is used to perform the method according to any one of claim 1 to 26.

A kind of 43. systems for passing through the deformation of the workpiece manufactured by increasing material manufacturing for prediction, wherein, the manufacture includes will be logical The material for crossing thermal source fusing is deposited on substrate along deposition path, and the system includes：

Main storage, the main storage is used for storage for the computer-readable code of Finite Element Method ＆ Its Application module；

At least one processor, at least one processor is attached to the main storage, and at least one processor is held The computer-readable code in the row main storage so that the application module to the workpiece before manufacture and system The thermomechanical model of finite element during making carries out finite element analysis, to predict the shape distortion and/or residual stress development of workpiece.